To obtain a motor drive capable of high speed rotation in which stabilized rotation is enabled even in a state that a positional estimation error of a rotor increases at a high rate.
Without altering a voltage saturation rate set value compared with a voltage saturation rate, i.e. the degree of the voltage saturation of a voltage command value applied to a motor 3, a speed proportional integration operation gain switching means 11 compares the voltage saturation rate with the voltage saturation rate set value and switches the gain set value of proportional integration operation for determining a command speed from the estimated number of revolutions and a target speed only when the voltage saturation rate is not lower than the voltage saturation rate set value.
NOMA HIROBUMI
KUBOTA FUTOSHI
Tomoyasu Sakaguchi
Hiroki Naito
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